If you know that you have prediabetes, you can think of yourself as being especially lucky. You can take your diagnosis as a wake-up call. Or, as the Certified Diabetes Educator Susan Semb calls it in the subtitle of her book Prediabetes, it is “an opportunity.”

Of the five big studies of prediabetes, the biggest one and the one closest to home for most of us here was the U.S. Diabetes Prevention Program, or DPP. The New England Journal of Medicine published this study in 2002.

The DPP was multicenter study of 3,234 American adults comparing the effectiveness of a lifestyle intervention of weight loss and physical activity with a drug intervention – metformin – and with a placebo control group. In this three-year study those people who lost just 7 percent of their total body weight reduced their risk of getting diabetes by 58 percent. In fact, actual results showed that a weight loss of just 5 percent was significant for the prevention of diabetes. Lifestyle modification was especially valuable for people 65 years of age and older. Their risk of getting diabetes was cut by 71 percent.

China Leads the World in Prediabetes

This study is of great importance because a huge number of Americans have prediabetes and are therefore at risk of getting diabetes. But China has far more people with prediabetes.

Fully half of all the adults in China have prediabetes, according to a survey by Chinese researchers that the journal of the American Medical Association published in 2013. This means that half a billion people in that country alone have this condition.

This makes the China Da Qing Diabetes Prevention Outcomes Study, which The Lancet published in 2008, especially important. This multicenter study of 577 adults in mainland China found that a lifestyle intervention of weight loss and physical activity reduced the risk of people there getting diabetes by 51 percent.

The Indian Diabetes Prevention Programme studied 531 people for an average of about 30 months. This study found that lifestyle modifications reduced the risk of people there getting diabetes by 29 percent.

Weight Loss Works in Scandinavia Too

Of the five big studies of prediabetes, the other two are from Scandinavia. And two major articles report on the Finnish Diabetes Prevention Study of more than 500 people for about three years. The study in The New England Journal of Medicine came out in 2001 and Diabetes Care reported it two years later.

This Finnish study found that the overweight people who were in the lifestyle intervention group reduced their risk of type 2 diabetes by 58 percent, which happens to be exactly the same proportion that the DPP found.

From Sweden, the Malmo feasibility study of 181 middle-aged men showed that even a modest weight loss led to better blood glucose control. Half of the people in the intervention group returned to normal blood glucose levels.

How Doctors Diagnose Prediabetes

Some of these studies write about to impaired glucose tolerance, where people have high blood glucose levels after eating, or impaired fasting glucose, where they have high levels after they fast. But prediabetes is the term the researchers now generally use to describe both of these conditions. It is “a gray area between normal glucose levels and diabetes,” the International Diabetes Federation says.